The present invention relates to an apparatus and a method for preventing rotation of a nozzle segment in a gas turbine while also facilitating removal and replacement/installation of a selected nozzle segment without having to remove the upper turbine shell or casing.
In gas turbines, individual nozzle stages are typically formed by an annular array of nozzle segments spaced circumferentially one from the other about the axis of the turbine. For example, in a simply supported nozzle segment design (for example, in a turbine first stage), the nozzle segments each include outer and inner bands with one or more nozzle vanes extending therebetween, and with mounting constraints at the inner and outer bands. Oftentimes, however, it is necessary to remove the upper or outer turbine shell in order to gain access to and remove a sample or damaged nozzle segment for testing and/or repair or replacement. Therefore, there is a need to generally improve the capability for removing and installing one or more selected nozzle segments to facilitate maintenance and/or testing operations.